Fig 1. Comparison of bacterial invasiveness after grown in different brands of LB-Miller.

A. Invasion assays were conducted on HeLa cells using SL1344 bacteria grown in US Biological (US-B), Difco, or Sigma LB-Miller. Data are % of the inoculum found to be intracellular at 1.5 h post-infection, normalized to US-B invasion from n = 3, showing mean ±SD. Plate reader growth curves (B) and PprgH activity (C) of the SPI-1 reporter strain (PprgH-gfp [LVA]) are shown for one representative experiment (n = 3). D. % promoter activity was calculated from n = 3 of GFP/OD600 at maximum promoter activity; normalized to US-B LB-M grown bacteria. Data are mean ±SD; statistical analyses were done using a one-way ANOVA with Dunnett’s multiple comparisons test (* p < 0.05).